Field of the Invention
The present invention relates to an image forming apparatus and a control program.
Description of the Related Art
There is a demand for a decrease in the burden imposed on a user when a paper jam occurs in an image forming apparatus. When a paper jam is detected in a sheet conveyance path in which paper sheets are conveyed, an image forming apparatus normally suspends the printing process being currently carried out, and starts a jam clearing process to return to the normal sheet conveyance that was being performed before the paper jam occurred. At that time, the sheet conveyance in the sheet conveyance path is also suspended. As a result, some paper sheets might remain in the sheet conveyance path. A paper sheet remaining in the sheet conveyance path will be hereinafter also referred to as a “remaining paper sheet”.
In a jam clearing process, an image forming apparatus normally prompts the user to remove the remaining paper sheets that might hinder the later sheet conveyance from the sheet conveyance path. The remaining paper sheets to be removed includes the paper sheet that has caused the paper jam (this paper sheet will be hereinafter referred to as the “jam causing sheet”), for example. This is because it is often difficult to mechanically remove the remaining paper sheet that might hinder sheet conveyance, and the user needs to remove such a remaining paper sheet. To reduce the load on users in this regard, some of the recently developed image forming apparatuses have a function to display information, such as the position of a jam causing sheet and a sheet removing method, on a touch panel display or the like.
To reduce the load on users, some image forming apparatuses further have a function to automatically discharge remaining paper sheets in the sheet conveyance path, without any help from user-s. After the above mentioned remaining paper sheets that might hinder the sheet conveyance are removed by a user, paper sheets that do not hinder the sheet conveyance might remain in the sheet conveyance path. In a case where such paper sheets that do not hinder sheet conveyance remain in the sheet conveyance path, the image forming apparatus mechanically and automatically conveys the paper sheets, and discharges the paper sheets to the outside of the image forming apparatus (this discharge of remaining paper sheets will be hereinafter referred to as “automatic discharge”).
Paper sheets in an image forming apparatus are normally managed and conveyed in accordance with a print job the image forming apparatus receives from a client terminal or the like. When sheet conveyance in the sheet conveyance path is suspended due to a jam clearing process or the like, the image forming apparatus saves the states of the respective remaining paper sheets. When the sheet conveyance is resumed later, and the remaining paper sheets are automatically discharged, the image forming apparatus performs sheet conveyance in accordance with the print job and the saved states of the remaining paper sheets (see JP 2005-84234 A, for example).
However, to remove a remaining paper sheet such as a jam causing sheet that hinders automatic discharge, a user opens a door on the front side of the image forming apparatus, and pulls out the rack in which the sheet conveyance path is accommodated. In doing so, the user might notice a remaining paper sheet that can be automatically discharged, and inadvertently remove the remaining paper sheet. Furthermore, when operating a cancellation lever, the user might greatly move the remaining paper sheet that can be automatically discharged, and cause overlapping between the remaining paper sheets. As a result, when automatic discharge is started, the saved states of the remaining paper sheet grasped by the image forming apparatus might differ from, the states of the actual remaining paper sheets in the sheet conveyance path. In this case, the image forming apparatus faces an unexpected situation where remaining paper sheets that should be there have disappeared, remaining paper sheets overlap each other, remaining paper sheets have changed positions, or the like. As a result, conveyance of the remaining paper sheets might fail.
As described above, if the states of remaining paper sheets that can be automatically discharged have changed after suspension of sheet conveyance in the sheet conveyance path, the image forming apparatus might fail to automatically discharge the remaining paper sheets properly.